Fuel blending system method and apparatus

Abstract

The system is an on-board and in-line system for blending two fuels of known characteristics to achieve instantaneous in-line change in the octane rating of fuel flowing to the engine. The blending system provides a means of precise in-line blending of two reference fuels in an on-board aircraft or land vehicle installation. Based on appropriate calibration blending curves, the system will provide instantaneous indications of both lean and rich performance ratings of the fuel. Instantaneous lean and rich performance ratings of the blended fuel streams may be recorded concurrently with engine parameters and ambient test data, and with combustion knock severity numbers derived from the previously mentioned detonation indication system.

I claim: 
     
       1. An on-board fuel blending system of two reference fuels A and B of known octane ratings for a piston engine comprising: first and second fuel tanks with discharge lines each containing respective test fuels A and B;   a constant pressure pump having a discharge line connected to the discharge line of each tank for supplying a constant pressure of both fuel A and fuel B;   an adjustable blending valve with two entry ports and one exit port, each entry port connected to the discharge line of the respective pumps of fuels A and B, the blending valve includes a spool means which as it moves, increases the portion of one reference fuel as it decreases the portion of the other fuel to vary the octane rating of the blended-flow from the exit port;   a first flow meter in the flow path of one of the constant pressure pumps;   a second flow meter in the flow path of the blended flow flowing from the blending valve;   a float controlled needle valve positioned in the mixed fuel flow path which limits the mixed fuel flow to that which the engine is burning; and   integral processing means which senses the flow from both said flow meters to compute the percent of each test fuel A and B in the blend and the octane rating of the blended stream.   
     
     
       2. An on-board fuel blending system as set forth in claim 1, wherein the discharge line of each constant pressure pump includes a vapor separator upstream of the first flow meter and the blending valve. 
     
     
       3. An on-board fuel blending system as set forth in claim 1, wherein the discharge line of each constant pressure pump includes a vapor separator upstream of the first flow meter and the blending valve, and a vent line connected downstream of said float controlled needle valve including therein a low pressure regulating means to provide back pressure to the blended fuel flowing to the engine. 
     
     
       4. An on-board fuel blending system as set forth in claim 1, wherein the discharge line of each constant pressure pump includes a vapor separator upstream of the first flow meter and the blending valve, and low pressure regulating means downstream of the float control needle valve to provide back pressure to the blended fuel flowing to the engine. 
     
     
       5. An on-board fuel blending system as set forth in claim 1, wherein the blending valve has manual operating knob for shifting the spool means to adjust the octane rating of the blended fuel flowing therefrom. 
     
     
       6. An on-board fuel blending system as set forth in claim 1, which is used on a fuel injection system having a return flow from the injector system and includes a return line connected to the float chamber of said float control needle valve, the level of which controls the operation of the valve and determines the overall flow rate passing through the blending valve. 
     
     
       7. An on-board fuel blending system as set forth in claim 1, including a three-way valve positioned in the blended-fuel flow path downstream of the float controlled valve having a second position which blocks the blended fuel flow to the engine and opens the engine to the fuel in the main tanks of the, aircraft. 
     
     
       8. A method of achieving instantaneous known octane rating changes in the on-line fuel flow to a piston engine comprising the steps of: supplying to an adjustable ratio blending valve a constant pressure supply of two reference fuels of known octane characteristics;   measuring the flow rate of one of the two known octane reference fuels, to the blending valve;   measuring the total blended flow rate from the blending valve of the combined fuels;   adjusting the flow rate of the total blended fuels from the blending value to correspond with the actual burn rate of the engine; and   sensing the two flow rates, computing the octane rating of the on-line blend flowing to the engine.   
     
     
       9. An on-board fuel blending system, as set forth in claim 1, wherein the computer means also senses and records detonation data along with other engine operating parameters in conjunction with the specific octane levels of the blended mixture.